Effluent monitoring -alcohol ethoxylate

Summary

The ERASM Environmental Monitoring and Analysis Task Force validated a suitably sensitive and specific analytical method capable of quantifying all alcohol and ethoxymer species in the range C12-18EO0-18 in effluents and has applied this to a number of fate and monitoring studies. This method provides a complete environmental fingerprint of alcohol ethoxylates [AEs]. Data from these studies have provided the ERASM Complex Substance Aquatic Risk Assessment [CSARA] Task Force with useful data to conduct an ecotoxicological risk assessment.

Background

The ecotoxicological risk assessment is a pivotal part of the chemical legislation (e.g. REACH) based on the comparison of environmental concentrations, the predicted environmental concentration [PEC] value in legal terms, and the concentration that is perceived to be safe for aquatic organisms (Predicted No Effect Concentration [PNEC]). To determine the PEC various methods can be taken into account. Among these methods the systematic determination of environmental concentrations based in the aquatic environment (environmental monitoring) deserves the highest credibility. This project focused on the development of a specific and sensitive analytical method for all alcohol and ethoxymer species in the range C12-18EO0-18, which would provide a complete environmental fingerprint of AEs.

Outcome

A specific derivatisation method which permitted trace detection (ng/L) by electrospray LC/MS of up to 114 individual alcohol and ethoxymer species in the range C12-18EO0-18 was validated for effluent samples. Representative samples of effluents from European activated sludge wastewater treatment plants [WWTPs] and from a variety of WWTPs in Canada were forwarded for analysis using the LC/MS method.

The range and mean of AE results for the two sampling surveys were very similar with an overall mean AE level of 5.7 µg/L and range 1.0 – 22.7 µg/L (Eadsforth et al. 2006). Similar AE levels in effluents (range 1.2 – 20.7 µg/L, mean 7.2 µg/L) were observed in a US study . This analytical method was also successfully used to determine the contribution of AE-derived fatty alcohols [AOH] to the total concentration of AE and AOH in a laboratory continuous activated sludge [CAS] study (Wind et al. 2006) . Removal of AEs ranged from 99.70% for C18 components and > 99.98% for C12-16 components. It was shown that AOH only represented 19% of the total AE in the CAS, whereas a much higher AOH percentage (55%) was found in effluents from European, Canadian and US WWTPs.

Data from these monitoring and fate studies have been used by the ERASM Complex Substance Aquatic Risk Assessment [CSARA] Task Force to develop a refined QSAR based on the ethoxymer distribution (Boeije et al. 2006) and to undertake a refined aquatic risk assessment of alcohol ethoxylates in North America and Europe (Belanger et al. 2006).